What is the ruling on performing cosmetic surgery on a child with Down syndrome?

If a person has a disfigurement that mars their appearance, there is no objection to them undergoing an operation to remove this disfigurement. The basis for this is what Abu Dawud narrated from Arfajah ibn Sa’d, may Allah be pleased with him: "His nose was cut off on the Day of al-Kilab, so he fashioned a nose of ورق (silver), but it caused a bad odor. The Prophet, peace and blessings be upon him, then commanded him to fashion a nose of gold."

Therefore, performing such a procedure in this situation is not considered an alteration of Allah's creation, which is forbidden in Islamic law, as stated in His Almighty's saying: "And I will surely command them, and they will alter the creation of Allah" (An-Nisa: 119).